Editing Triboelectric effect (section)

=== Triboelectric series ===
[[File:Triboelectric-series_EN.svg|thumb|right|A simple triboelectric series]]

An empirical approach to triboelectricity is a triboelectric series''.'' This is a list of materials ordered by how they develop a charge relative to other materials on the list. [[Johan Carl Wilcke]] published the first one in a 1757 paper.<ref name=":35" /><ref name="Dictionary of Scientific Biography" /> The series was expanded by Shaw<ref name=":19" /> and Henniker<ref name=":32" /> by including natural and synthetic polymers, and included alterations in the sequence depending on surface and environmental conditions. Lists vary somewhat as to the order of some materials.<ref name=":19">{{Cite journal |last=Shaw |first=P. E. |date=1917 |title=Experiments on tribo-electricity. I.—The tribo-electric series |journal=Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character |volume=94 |issue=656 |pages=16–33 |doi=10.1098/rspa.1917.0046 |bibcode=1917RSPSA..94...16S |issn=0950-1207|doi-access=free }}</ref><ref name=":32">{{Cite journal |vauthors=Henniker J |date=1962 |title=Triboelectricity in Polymers |journal=Nature |volume=196 |issue=4853 |page=474 |bibcode=1962Natur.196..474H |doi=10.1038/196474a0 |s2cid=4211729|doi-access=free }}</ref>

Another triboelectric series based on measuring the triboelectric charge density of materials was proposed by the group of [[Zhong Lin Wang]]. The triboelectric [[charge density]] of the tested materials was measured with respect to liquid mercury in a [[glove box]] under well-defined conditions, with fixed temperature, pressure and humidity.<ref name=":0">{{cite journal |display-authors=6 |vauthors=Zou H, Zhang Y, Guo L, Wang P, He X, Dai G, Zheng H, Chen C, Wang AC, Xu C, Wang ZL |date=2019 |title=Quantifying the triboelectric series |journal=Nature Communications |volume=10 |issue=1 |page=1427 |bibcode=2019NatCo..10.1427Z |doi=10.1038/s41467-019-09461-x |pmc=6441076 |pmid=30926850}}</ref><ref>{{Cite journal |last1=Zou |first1=Haiyang |last2=Guo |first2=Litong |last3=Xue |first3=Hao |last4=Zhang |first4=Ying |last5=Shen |first5=Xiaofang |last6=Liu |first6=Xiaoting |last7=Wang |first7=Peihong |last8=He |first8=Xu |last9=Dai |first9=Guozhang |last10=Jiang |first10=Peng |last11=Zheng |first11=Haiwu |last12=Zhang |first12=Binbin |last13=Xu |first13=Cheng |last14=Wang |first14=Zhong Lin |date=2020-04-29 |title=Quantifying and understanding the triboelectric series of inorganic non-metallic materials |journal=Nature Communications |language=en |volume=11 |issue=1 |page=2093 |doi=10.1038/s41467-020-15926-1 |issn=2041-1723 |pmc=7190865 |pmid=32350259|bibcode=2020NatCo..11.2093Z }}</ref>
[[File:Cyclic triboelectric series example.png|thumb|Cyclic triboelectric series example, illustrating that a linear approach does not work in practice]]
It is known that this approach is too simple and unreliable.<ref name=":1" /><ref name=":2" /><ref name=":3">{{Cite journal |last1=Lowell |first1=J. |last2=Rose-Innes |first2=A.C. |date=1980 |title=Contact electrification |journal=Advances in Physics |volume=29 |issue=6 |pages=947–1023 |doi=10.1080/00018738000101466 |bibcode=1980AdPhy..29..947L |issn=0001-8732}}</ref> There are many cases where there are triangles: material A is positive when rubbed against B, B is positive when rubbed against C, and C is positive when rubbed against A, an issue mentioned by Shaw in 1914.<ref name=":33" /> This cannot be explained by a linear series;  cyclic series are inconsistent with the empirical triboelectric series.<ref>{{Cite journal |last1=Pan |first1=Shuaihang |last2=Zhang |first2=Zhinan |date=2019 |title=Fundamental theories and basic principles of triboelectric effect: A review |journal=Friction |volume=7 |issue=1 |pages=2–17 |doi=10.1007/s40544-018-0217-7 |s2cid=256406551 |issn=2223-7690|doi-access=free }}</ref> Furthermore, there are many cases where charging occurs with contacts between two pieces of the same material.<ref>{{Cite journal |last1=Lowell |first1=J. |last2=Truscott |first2=W. S. |date=1986 |title=Triboelectrification of identical insulators. I. An experimental investigation |url= https://iopscience.iop.org/article/10.1088/0022-3727/19/7/017 |journal=Journal of Physics D: Applied Physics |volume=19 |issue=7 |pages=1273–1280 |doi=10.1088/0022-3727/19/7/017 |bibcode=1986JPhD...19.1273L |s2cid=250769950 |issn=0022-3727}}</ref><ref>{{Cite journal |last1=Lowell |first1=J. |last2=Truscott |first2=W. S. |date=1986 |title=Triboelectrification of identical insulators. II. Theory and further experiments |url= https://iopscience.iop.org/article/10.1088/0022-3727/19/7/018 |journal=Journal of Physics D: Applied Physics |volume=19 |issue=7 |pages=1281–1298 |doi=10.1088/0022-3727/19/7/018 |bibcode=1986JPhD...19.1281L |s2cid=250811149 |issn=0022-3727}}</ref><ref name=":9">{{Cite journal |last1=Baytekin |first1=H. T. |last2=Patashinski |first2=A. Z. |last3=Branicki |first3=M. |last4=Baytekin |first4=B. |last5=Soh |first5=S. |last6=Grzybowski |first6=B. A. |date=2011 |title=The Mosaic of Surface Charge in Contact Electrification |journal=Science |volume=333 |issue=6040 |pages=308–312 |doi=10.1126/science.1201512 |pmid=21700838 |bibcode=2011Sci...333..308B |s2cid=18450118 |issn=0036-8075|doi-access=free |hdl=20.500.11820/f416715b-eaa4-4051-a054-a6cd527a6066 |hdl-access=free }}</ref> This has been modelled as a consequence of the electric fields from local bending ([[flexoelectricity]]).<ref name=":5" /><ref name=":26" /><ref name=":25">{{Cite journal |last=Persson |first=B. N. J. |date=2020 |title=On the role of flexoelectricity in triboelectricity for randomly rough surfaces |url= https://iopscience.iop.org/article/10.1209/0295-5075/129/10006 |journal=EPL (Europhysics Letters) |volume=129 |issue=1 |page=10006 |doi=10.1209/0295-5075/129/10006 |arxiv=1911.06207 |bibcode=2020EL....12910006P |s2cid=208615180 |issn=1286-4854}}</ref>